An area in Hong Kong’s New Territories still faces the threat of flash floods after the Drainage Services Department admitted that a nearby river lacked adequate drainage capacity.

The admission followed two days of heavy rain in the city, which prompted authorities to issue the amber rainstorm warning signal three times within a day. An amber alert means rainfall exceeds “30mm in an hour” and is “likely to continue”.

The rain severely hit Tai Po – located in the east of Hong Kong – flooding areas such as the Pat Sin Leng mountain range to villages in Tai Mei Tuk, Ting Kok and Shan Liu along Ting Kok Road.

Ho Yiu-kwong of the Drainage Services Department said the drainage capacity of a river near Ting Kok village was assessed to be “a bit inadequate”.

“We saw debris and tree branches blocking the upper stream of the river, which further worsened the drainage capacity,” Ho, the department’s chief engineer of land drainage, told an RTHK radio show on Wednesday morning.

He said that the department had been clearing debris in the river since March. A current review on the drainage plan for Tai Po district would be completed by early next year.

In the meantime, the department would draft a long-term solution to alleviate the flooding problem, he said.

Lau Chee-sing, a Tai Po district councillor in the constituency of Shuen Wan, which covers the area affected by the flood this week, argued that the river must be trenched deeper after the accumulation of debris.

“Drainage capacity of the river might have been reduced by half,” he said at the same radio show. “When there is a heavy downpour, the river cannot carry all the water, which will overflow to houses on both sides of the river.”

Lau also accused the department of dragging its feet over the review of the Tai Po drainage plan.

But Ho responded that the river had been naturally formed and has ecological value.

“We need to study how to balance the two sides – by not affecting the ecology while reducing the risk of flooding,” Ho said.

Leung Pak-keung, head of Shan Liu village, blamed government departments for the flood, accusing them of not clearing the drains in the nearby catchment area on a regular basis.

Even though the flood water, which at one point reached up to the knees and flowed into houses, has subsided, Leung expected that it would take around a week for villages to clean up the scene.